1. Field of the Invention
This invention relates to an epoxy resin composition which has the ability to prevent migration of gold, silver, copper, etc. used as circuits in electronic component parts and printed base boards, and possesses excellent heat resistance, chemical resistance, moisture resistance, adhesion and insulation. It is useful, for example, for the production of sealing materials for electronic component parts, inks, insulating paints and adhesives for printed circuit base boards, and copper-clad laminated boards.
2. Description of the Prior Art
Epoxy resins have found widespread use in various industrial fields because they cure with, for example, aliphatic amines, aromatic amines, tertiary amines, polyamide resins or acid anhydrides to give resins having excellent heat resistance, electrical insulation and adhesion. Especially, it is known that blending of a certain imidazole compound, a kind of tertiary amine, with an epoxy resin can give a one-package epoxy resin composition having good workability or handlability and being capable of giving a cured product having excellent heat resistance (see U.S. Pat. No. 4,205,156).
With the recent tendency to the smaller sizes, lighter weights and higher densities of electronic appliances and component parts, epoxy resins for sealing are required to have high insulating property and heat resistance.
Inks and insulating paints for printed circuit base boards and copper-clad laminated boards have been required likewise to have high insulation and heat resistance in fine and multilayered printed circuits. Furthermore, the prevention of migration of silver or copper constituting the circuits has also been rigorously required. Various resins have been developed and marketed in an attempt to meet these requirements, but none have proved to be entirely satisfactory in workability or handlability or in other properties. For example, these resins are not entirely satisfactory in regard to curing conditions and pot lives, or have large shrinkage on curing or low adhesion.